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Title: The production and characterisation of photocatalytic titania coatings by different pulsed magnetron sputtering techniques
Author: Farahani, Nick
ISNI:       0000 0004 2745 0837
Awarding Body: Manchester Metropolitan University
Current Institution: Manchester Metropolitan University
Date of Award: 2012
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It is well known that, depending on deposition conditions, the structure of titania coatings may be amorphous, brookite, anatase or rutile, or a mixture of phases, and that the anatase phase is the most promising photocatalyst for the degradation of organic pollutants. The formation of anatase depends on the energy delivered to the growing film, which in turn depends on the operating parameters chosen. In this study, coatings have been deposited onto glass substrates by pulsed magnetron sputtering (100 - 350 kHz) both from metallic targets in reactive mode and directly from oxide powder targets. In the former case, initially FFE (full face erosion) magnetrons were used. The FFE magnetrons have the capability to oscillate the central pole in the magnetic array. This is designed to increase the area of the target that is sputtered, which improves target utilisation and, by keeping the central region of the target clean, also improves process stability by reducing the tendency for arcing. In this particular study; a model (that complies with Lobi's) was presented in which new influential factors in pulse magnetron sputtering (such as pulse frequency, duty cycle and FFE oscillation speed) have been considered. Further sets of coatings have been produced both from metallic and powder targets in which the titania is doped with tungsten, niobium or zinc ferrite. The powder sputtering technique used here was an economic way of testing dopant materials before going to the expense of purchasing a full size sputtering target. The as-deposited coatings were analysed by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and micro Raman spectroscopy. Selected coatings have been annealed at temperatures in the range of 100 - 700°C and re- analysed. The photocatalytic activity of the coatings has been investigated through measurements of the degradation of organic dies, such as resazurin and methyl orange, under the influence of UV and fluorescent light sources. The resazurin test provided a quick indication of whether the surfaces were active or not. However, the level of photocatalytic activity was quantitatively assessed by the methyl orange tests performed on the coatings annealed at optimum temperature of 700°C. In this study for both sets of experiments; reactively and directly sputtered titanial titania doped coatings; the influence of deposition parameters (such as pulse frequency and duty) and its relation to the structures/ properties of the as-deposited/ post-annealed coatings has been investigated.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available